KR20080050862A - Method of preparing electrode of solar cell, method of preparing solar cell, and solar cell - Google Patents

Abstract

A method for forming an electrode of a solar cell, a method for manufacturing the solar cell, and the solar cell are provided to reduce the reflectance of the solar cell and to increase a thickness of an electrode line by reducing a width of the electrode line. A mold(301) is manufactured according to an electrode pattern. A paste for forming an electrode is injected into the mold and then hardened to form an electrode line(311). The electrode is attached to an adhesive tape(303) where an adhesive is covered. The electrode attached to the adhesive tape is attached to a substrate by using an adhesive agent of which adhesive strength is stronger than that of a gluing agent. The adhesive tape is separated from the electrode line. A heat treatment is performed on the electrode line formed on the substrate. The paste includes silver, a glass frit, and a binder. The adhesive agent is selected from a group consisting of a rubber-based adhesive, an acrylate-based adhesive, and a silicon-based adhesive.

Description

Method of preparing electrode of solar cell, method of manufacturing solar cell and solar cell {Method of preparing electrode of solar cell, method of preparing solar cell, and solar cell}

The following drawings attached to this specification are illustrative of preferred embodiments of the present invention, and together with the detailed description of the invention to serve to further understand the technical spirit of the present invention, the present invention is a matter described in such drawings It should not be construed as limited to.

1 is a schematic diagram showing the basic structure of a solar cell.

2 is a view schematically showing the structure of a typical solar cell.

3 to 7 are views for illustratively explaining the electrode forming method of the present invention.

The present invention relates to a method for forming an electrode of a solar cell, a method for manufacturing a solar cell, and a solar cell, and more particularly, to reduce the width of an electrode line to increase absorption of sunlight and reduce the resistance of an electrode. It relates to a method of forming an electrode of a battery, a method of manufacturing a solar cell including the same, and a solar cell manufactured using the same.

Recently, as the prediction of depletion of existing energy sources such as oil and coal is increasing, interest in alternative energy to replace them is increasing. Among them, solar cells are particularly attracting attention because they are rich in energy resources and have no problems with environmental pollution. Solar cells include solar cells that generate steam for rotating turbines using solar heat, and solar cells that convert photons into electrical energy using the properties of semiconductors. Refers to photovoltaic cells (hereinafter referred to as solar cells).

Referring to FIG. 1 showing the basic structure of a solar cell, a solar cell has a junction structure of a p-type semiconductor 101 and an n-type semiconductor 102 like a diode, and when light is incident on the solar cell, Interaction with the materials that make up the semiconductor causes electrons with negative charge and electrons to escape, creating holes with positive charge, and as they move, current flows. This is called a photovoltaic effect. Among the p-type 101 and n-type semiconductors 102 constituting the solar cell, electrons are directed toward the n-type semiconductor 102 and holes are p-type semiconductors ( Pulled toward 101 and moved to the electrodes 103 and 104 bonded to the n-type semiconductor 101 and the p-type semiconductor 102, respectively, and when the electrodes 103 and 104 are connected by wires, electricity flows. Can get

In general, the output characteristics of such a solar cell have a total light energy (S ×) incident on the solar cell at a maximum value Pm of the product Ip × Vp of the output current Ip and the output voltage Vp on the output current voltage curve obtained using the solar simulator. I: S is the device area, and I is the conversion efficiency η divided by the intensity of light irradiated to the solar cell).

In order to improve the conversion efficiency of the solar cell, it is necessary to increase the reflectance of the solar cell to sunlight, reduce the degree of recombination of carriers, and lower the resistance of the semiconductor substrate and the electrode. Research on solar cells is largely underway.

Electrode formation of such a solar cell is generally made through a process of applying an electrode forming paste to a semiconductor substrate or an antireflection film according to a predetermined pattern and then heat-treating. However, according to this method, the electrode-forming paste does not maintain its shape until it cures, and flows down to the side, making it difficult to form electrodes according to a predetermined pattern, and it is difficult to form electrode lines thinly, thereby limiting the reflectance of the battery. . In addition, the electrode-forming paste contains a large amount of a substance other than a metal such as glass frit, thereby increasing the resistance of the electrode.

Therefore, efforts to solve such problems of the electrode forming method of the solar cell have been made in the related field steadily, and the present invention has been devised under such technical background.

The present invention has been made to solve the above-mentioned problems of the prior art, the technical problem to be achieved by the present invention is to improve the electrode forming method of the solar cell to reduce the width of the electrode line at the same time lowering the reflectance to sunlight and the electrode The purpose of the present invention is to improve the efficiency of solar cells by reducing the resistance of the present invention, and to provide a method for forming an electrode of a solar cell, a method for manufacturing a solar cell, and a solar cell, which can achieve the technical problem.

The present invention to achieve the technical problem to be achieved by the present invention, (S1) manufacturing a mold according to the electrode pattern; (S2) forming an electrode line by injecting an electrode forming paste into the mold and curing the paste; (S3) attaching the electrode line to a pressure-sensitive adhesive tape; (S4) attaching the electrode line attached to the adhesive tape on a substrate using an adhesive having a stronger adhesive force than the adhesive, and separating the adhesive tape from the electrode line; And (S5) heat-treating the electrode line formed on the substrate. It provides an electrode forming method of a solar cell comprising a.

The paste may typically be made of silver, glass frit, and a binder, and the adhesive may be a rubber-based (silicone rubber, isoprene rubber) adhesive, an acrylate-based adhesive, or a silicone-based adhesive. Etc. may be used, and as the adhesive, an isocyanate-based or epoxy adhesive may be used.

The present invention also provides a method of manufacturing a solar cell comprising the electrode forming method of the present invention described above.

The present invention also provides a solar cell manufactured using the solar cell manufacturing method of the present invention described above.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings to assist in understanding the present invention.

2 is a view schematically showing the structure of a typical solar cell. As shown in FIG. 2, a solar cell is usually formed on a first conductivity type semiconductor substrate 201 and the first conductivity type semiconductor substrate 201 and is opposite to the first conductivity type semiconductor substrate 201. Pn structure including a second conductive semiconductor layer 202 having a pn junction formed at an interface between the first conductive semiconductor substrate 201 and the second conductive semiconductor layer 202, and for reducing reflectance An anti-reflection film 205 formed on the second conductive semiconductor layer, a front electrode 203 formed through the anti-reflection film and connected to the second conductive semiconductor layer, and a rear electrode formed on the first conductive semiconductor substrate. 204 and a BSF layer 206 formed on a contact surface of the back electrode and the first conductivity type substrate.

The present invention relates to a method for forming the front electrode 203 and the rear electrode 204 of such a solar cell, the method of forming an electrode of the present invention (S1) manufacturing a mold according to the electrode pattern; (S2) forming an electrode line by injecting an electrode forming paste into the mold and curing the paste; (S3) attaching the electrode line to a pressure-sensitive adhesive tape; (S4) attaching the electrode line attached to the adhesive tape on a substrate using an adhesive having a stronger adhesive force than the adhesive, and separating the adhesive tape from the electrode line; And (S5) heat treating the electrode line formed on the substrate.

3 to 7 are views for illustratively explaining the electrode forming method of the present invention. An electrode forming method of the present invention will be described with reference to FIGS. 3 to 7.

According to the electrode forming method of the present invention, first, a mold 301 according to the electrode pattern is manufactured as shown in FIG. 3. Since the rear electrode is generally formed on the entire surface of the first conductivity type substrate, the electrode forming method of the present invention may be more effectively used for forming the front electrode. In forming the front electrode, an area occupied by the electrode and the shape of the electrode can be appropriately selected in consideration of reflectance to sunlight and contact resistance between the front electrode and the second conductive semiconductor layer. The material of the mold 301 is not particularly limited, and typically, poly-dimethyl-siloxane (PDMS), a metal alloy, or the like may be preferably used.

When the mold 301 is formed, an electrode forming paste is injected into the mold 301 and cured to form an electrode line 311. The composition of the electrode forming paste is not particularly limited, but a paste including silver, glass frit, and a binder may be typically used for the front electrode, and other additives may be added to improve physical properties. By using the electrode forming method of the present invention, it is possible to reduce the content of the non-metallic material such as glass frit in the electrode forming paste, and to reduce the width of the electrode line and increase the thickness to lower the resistance of the electrode to improve the efficiency of the battery Can be.

When the electrode line 311 is formed, the electrode line 311 is attached to the adhesive tape 303 on which the adhesive is applied. This process separates the electrode line 311 from the mold 301 and then attaches the electrode line 311 to the adhesive tape, or the electrode line without removing the electrode line 311 from the mold 301. It is also possible by attaching 311 to the adhesive tape and then separating the mold 301. The composition of the pressure-sensitive adhesive is not particularly limited, but typically rubber-based (silicone rubber, isoprene rubber) pressure sensitive adhesive, acrylate pressure sensitive adhesive or silicone pressure sensitive adhesive may be used. 4 and 5 exemplarily show the latter case.

Next, as shown in FIG. 6, the electrode line 311 attached to the adhesive tape 303 is attached onto the substrate 305 using an adhesive having a stronger adhesive force than that of the adhesive. The adhesive having stronger adhesive strength than that of the adhesive is used to separate only between the electrode line 311 and the adhesive tape 303 while maintaining the bond between the substrate 305 and the electrode line 311. The composition of the adhesive is not particularly limited, but representatively, an isocyanate-based or epoxy-based adhesive may be used.

Next, the adhesive tape 303 is separated from the electrode line 311. Due to the difference in adhesive strength between the adhesive and the adhesive, when the substrate 305 and the adhesive tape 303 are pulled in the opposite direction to apply tension, only the adhesive tape 303 and the electrode line 311 are separated.

Finally, the electrode line 311 formed on the substrate 305 is heat treated. In the case of the front electrode, the electrode line 311 is formed on the anti-reflection film. The electrode line 311 may penetrate the anti-reflection film and be connected to the second conductive semiconductor layer through the heat treatment. In addition, in the case of the back electrode, a BSF layer is formed at a portion where the back electrode and the first conductive semiconductor substrate are in contact with each other through such heat treatment.

The manufacturing method of the solar cell of the present invention includes the electrode forming method as described above, comprising: forming a second conductive semiconductor layer 202, that is, an emitter layer, on the first conductive semiconductor substrate 201; Forming an anti-reflection film (205) on the second conductive semiconductor layer (202); Forming a front electrode 203 through the anti-reflection film 205 so as to be connected to the second conductive semiconductor layer 202; Forming a back electrode 204 on the side opposite to the front electrode 203 with the first conductive semiconductor substrate 201 interposed therebetween so as to be connected to the first conductive semiconductor substrate 201. Can be done. The electrode forming method may be employed in the forming of the front electrode 203 or the back electrode 204.

According to the method of manufacturing a solar cell of the present invention, first, a second conductive semiconductor layer 202 of the opposite conductivity type is formed on the first conductive semiconductor substrate 201 to form a p-n junction at an interface thereof. As the first conductive semiconductor substrate 201, a p-type silicon substrate is typically used. For example, an n-type dopant is applied to a p-type silicon substrate, and then heat-treated by applying an n-type dopant to the p-type silicon substrate. By allowing diffusion, pn junctions can be formed.

Next, an antireflection film 205 is formed on the second conductivity type semiconductor layer 202. The antireflection film 205 may be typically formed of silicon nitride, and chemical vapor deposition and plasma chemical vapor deposition may be used to form the antireflection film 205.

Finally, the front electrode 203 is formed to penetrate the anti-reflection film 205 to be connected to the second conductive semiconductor layer 202, and the front surface is disposed with the first conductive semiconductor substrate 201 interposed therebetween. The back electrode 204 is formed on the side opposite to the electrode 203 so as to be connected to the first conductivity type semiconductor substrate 201. The order of forming the front electrode 203 and the forming of the back electrode 204 may be reversed. It is also possible to heat-treat at the same time after applying each paste.

The solar cell manufactured by the manufacturing method has a low width of the electrode line due to the thinner electrode line, and reduces the width and thickness of the electrode line and increases the content of a nonmetallic material such as glass frit to form the electrode. It can be reduced, the resistance of the electrode is low, showing improved efficiency.

The terms or words used in this specification and claims should not be construed as being limited to the common or dictionary meanings, and the inventors can appropriately define the concept of terms in order to best describe their invention. Based on the principle, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention.

Therefore, the exemplary embodiments described herein are only exemplary embodiments of the present invention and do not represent all of the technical ideas of the present invention, and various equivalents and modifications that may substitute them at the time of the present application may be used. It should be understood that there may be.

According to the electrode forming method of the solar cell of the present invention, it is easy to adjust the shape and width of the electrode line, the width of the electrode line can be reduced to reduce the reflectance of the solar cell to the sunlight, the width of the electrode line In addition to increasing the thickness, it is possible to reduce the content of the non-metallic material such as glass frit to form the electrode can significantly lower the resistance of the electrode, it can significantly improve the efficiency of the solar cell.

Claims (6)

(S1) manufacturing a mold according to the electrode pattern; (S2) forming an electrode line by injecting an electrode forming paste into the mold and curing the paste; (S3) attaching the electrode line to a pressure-sensitive adhesive tape; (S4) attaching the electrode line attached to the adhesive tape on a substrate using an adhesive having a stronger adhesive force than the adhesive, and separating the adhesive tape from the electrode line; And (S5) heat-treating the electrode line formed on the substrate; electrode forming method of a solar cell comprising a. The method of claim 1, The paste comprises a silver, a glass frit and a binder, characterized in that the electrode forming method of the solar cell. The method of claim 1, The pressure-sensitive adhesive is a method of forming an electrode of a solar cell, characterized in that selected from the group consisting of a rubber-based adhesive, an acrylate-based adhesive and a silicone-based adhesive. The method of claim 1, The adhesive is a method for forming an electrode of a solar cell, characterized in that the isocyanate-based or epoxy-based adhesive. The method of manufacturing a solar cell comprising the electrode forming method according to any one of claims 1 to 4. A solar cell manufactured using the method of manufacturing a solar cell according to claim 5.

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